The show will soon return to its fourth season, and the single girls of ”Sex and the City” are ready for their very own authorized companion. But first, of course, they’ve got to shop around – and they won’t come cheap. ”It could be a very expensive project,” says a publisher who met with the show’s star, Sarah Jessica Parker, book packager Charles Melcher, and representatives of HBO.

According to insiders, the book – called ”The Joy of Sex and the City” – will be written by sex columnist Amy Sohn under a pen name and will include ”segment-by-segment synopses, interviews with the actors, and a paean to their beloved New York, which they view as a major character in the story.”

And in the spirit of Manolo Blahnik-loving Carrie Bradshaw, the lavishly illustrated hardcover might even come packaged in a shoebox. ”We are doing a ‘Sex and the City’ companion that will be the definitive place for fans to get behind-the-scenes information they can’t get anywhere else,” confirms an HBO spokesperson, adding that she could not comment on who the writer would be.